The present invention relates to a fin for use as a part of a finned coil assembly for use in a heat exchanger. More particularly, the invention relates to a fin having a structure which enhances the heat exchange between the atmosphere and heat exchange fluid contained within segments of tubes passing through multiple fins of a finned coil assembly.
Evaporators or plate-finned coil heat exchangers typically comprise a bundle of numerous lengths of pipe or tubing in a square or staggered array, with numerous fins in the form of plates slid over and cross-sectionally surrounding the tubes. The plate fins have holes or orifices that correspond with the tube array geometry. The heat exchanger generally includes a fan or blower that causes air to flow through the finned coil assembly where the air flows generally parallel with respect to the fins and perpendicular with respect to the tubes. Typically, the fins have a formed collar surrounding each orifice so that the tube extending through the orifice fits securely and snugly into the fin. The collar allows the fin to remain in good thermal contact with the tube, thereby providing good heat transfer into or out of the tube. It is also known to have a planar area surrounding the collar and to provide the plate used to make the fin with corrugations.
An example of one type of heat exchanger coil assembly using fins, where the fins are corrugated and have collars including a planar area surrounding the collars is disclosed in Bradley et al. U.S. Pat. No. 5,425,414, assigned to the assignee of the present invention. Among various structural distinctions, one significant difference between the present invention and the fins used in the coil assembly of the aforementioned patent is the orientation of the corrugations with respect to the air flow. In the patent, air flows transverse to the axes of the corrugations. In the present invention, air flows generally parallel to the axes of the corrugations.
The structure of the fin of the present invention, particularly in the interface areas where the major corrugations join the generally flat areas surrounding the collars, provides for localized heat transfer increases due to the promotion of beneficial turbulence and boundary layer mixing. In addition, the present invention has a particular ratio of amplitude and frequency of the major corrugations with reference to the generally flat areas surrounding the collars and the tubes that also enhances heat transfer. In this industry, subtle and apparently minor changes in geometry and structure significantly affect the heat transfer characteristics.